Medically reviewed by
Dacelin St Martin, MD
Triple board-certified in Sleep Medicine,
Internal Medicine, and Pediatrics.
Epidemiology | Sleep Physiology | Physiology of Drowsy Driving | High-Risk Groups | Helpful Tips | Evaluation | Sleeplessness & Chronic Conditions
Before midday on Feb 23, news began to circulate that pro golfer Tiger Woods was involved in a rollover single-vehicle accident.
First responders to the scene reported that Woods showed no sign of impairment, so what could have caused the accident?
Even though he was speeding, evidence indicates that it was speeding that likely caused the crash. A forensic expert stated that there’s a high possibility the pro golfer fell asleep at the wheel.
More Common than You May Think
Tiger Woods’ accident is not an isolated incident. The number of accidents caused by sleepy drivers is alarming, and the figures are considerably greater than many of us thought.
AAA, a not-for-profit organization, conducted in-depth research in 2018, and the findings are shocking.
Researchers found that drowsy driving in the US alone resulted in 328,000 crashes annually – a number 350% higher than official government figures. Of the 328,000 crashes, a total of 109,000 led to an injury, while 6,400 resulted in the loss of lives.
Driving when you are fatigued or deprived of adequate sleep is dangerous. Scientists explained that going 17 hours without sleep will make you drive like an “impaired” person who has a blood alcohol concentration (BAC) OF 0.05% – the legal drunk scale.
This article shares the significant factors that can make you easily predisposed to dozing off when driving and ways you can prevent them.
In polls conducted by the National Sleep Foundation and others, around 60 percent of drivers admit to driving while feeling sleepy, 40% have nodded off or fallen asleep while driving, and about 25 percent report drowsy driving at least once per month, and included the following data:[4,5,6]
- 50-70 percent of teenagers admit to drowsy driving in the past year, and 15% report doing so at least once per week.
- Sleepiness while driving is associated with a 2.5-fold increase in the risk of a motor vehicle crash.
- Drowsy driving accounts for an estimated one in six fatal crashes and one in eight crashes leading to hospitalization of the vehicle occupant(s).
- Self-reports and police reports may underestimate the actual frequency of crashes attributed to drowsiness and various co-factors, such as alcohol or suspected distraction.
- A study that used in-vehicle video cameras to assess drowsiness showed that it was a factor in 10% of all crashes and 11% of crashes resulting in significant property damage.
Sleep is not optional or something you can effectively hold at bay for an extended time through the use of stimulants or steadfast perseverance. It’s a neurobiological need controlled by your sleep-wake cycle.
The sleep-wake cycle is comprised of two mechanisms that control when and how we sleep. Sleep-wake homeostasis balances our need for sleep with wakefulness. As the day progresses to night, our drive for sleep increases. On the other hand, circadian rhythm is our 24-hour biological clock that determines when we sleep.
The longer you go without sleeping, the more your body demands it and the harder it’s to remain alert and awake, especially when you’re on the road.
Microsleeps or near sleep will have you nodding off intermittently, quashing your best intentions to complete your task at hand. When your sleep is restricted either by choice or a disorder, it throws your circadian rhythm out of sync, bringing about extreme sleepiness.
Physiology of Drowsy Driving
Drowsiness can influence many cognitive functions that are important for driving. Judgment, attention, executive function, cognitive processing speed, memory, reaction time, and muscular coordination can all be affected.
These executive functions can be compounded by microsleeps, which are brief, involuntary episodes of sleep, lasting from a fraction of a second up to 30 seconds.[9-13]
After 24 consecutive hours of being awake, the level of impairment resembles that seen in drivers with a blood-alcohol level of 0.08 percent (considered legally drunk across the United States). Similar effects are observed in patients with chronic sleep disruption due to untreated sleep disorders, such as obstructive sleep apnea (OSA).
Accidents, where drowsiness is a suspected contributor, tend to coincide with times of highest sleep propensity: early morning (midnight to 7 AM) and mid-afternoon (3 PM). These circadian factors are most evident among young drivers.
You Control Your Sleep
Losing a single night’s sleep alone can bring about uncontrollable short-term sleepiness. Also, cutting your sleep time by 1 to 2 hours every night can make you develop chronic sleepiness.
When you purposefully delay sleep onset, you make yourself more susceptible to developing a circadian sleep-wake disorder called delayed sleep-wake disorder. Over time you can reset your 24-hour biological clock, making it difficult to fall asleep and wake up on your regular schedule.
As a driver, sleep deprivation in any form can impair your performance and lead to avoidable accidents. Even if you’re only moderately sleepy, you’ll notice your reaction time is slower (as found in Woods’ accident), performance and vigilance decrease, and information processing is delayed.
Although drowsy driving is a common problem and can happen with any sleep-deprived driver, certain groups are recognized to be at higher risk than others for habitual drowsy driving and its consequences.
- Youth (especially males aged 16 to 25 years)
- Those with obstructive sleep apnea (OSA), narcolepsy, and other sleep disorders
- Night or rotating shift workers
- Sleep-deprived individuals, like caregivers
- Those who use sedating medications, substances, or alcohol
- Commercial drivers
- Law enforcement officers
- Medical staff
Tips to Avoid Drowsy Driving
- Get enough sleep.
- If possible, take a short nap between 15 to 20 minutes before embarking on any long drive.
- Employers should allow napping for night-shift workers.
- A stuffy vehicle interior can easily lull you to sleep. So, adjust your car vents or open the window to let in some fresh air.
- Avoid medications, such as muscle relaxants, tranquilizers, and narcotic pain relievers that can trigger sleepiness.
- Play some energetic music.
- Take a friend along if you want to embark on a long trip.
- Combat sleepiness with low-dose caffeine (about 2 cups of percolated coffee should do).
- Get alerting devices or alarms that wake you up when you begin showing signs of sleepiness.
- Try bright light treatment to overcome jet lag or circadian rhythm disruption.
- Night shift employees, like nurses, can use light-darkening curtains, fans, and white noise machines/apps to help them sleep better during the day.
The evaluation of high-risk drowsy drivers is twofold:
1) Identify patients with treatable causes of drowsiness who require further testing for diagnosis or who may benefit from disease-specific treatment
2) Identify high-risk behaviors or habits that can be addressed through counseling
The evaluation is quite similar to the one performed for patients with excessive daytime sleepiness.
As driving is a passive activity, it may uncover previously unrecognized or unreported daytime sleepiness. A drowsy driving crash or near-miss may be the first time a patient reports the symptom of excessive sleepiness to a healthcare provider.
Clinical History and Risk Factors Reviewed During an Evaluation
- Results from a polysomnogram can help diagnose conditions, like sleep apnea and narcolepsy.
- Medical or psychiatric conditions, which may interfere with sleep continuity and sleep quality, such as cardiopulmonary disorders, pain syndromes, and mood disorders
- Use of sedating medications, like benzodiazepines, nonbenzodiazepine hypnotics, opioids, and alcohol
- Driving conditions, such as long-distance, late at night, lone driving
- Circadian factors, such as night or rotating shift work or jet lag
- Lifestyle factors, such as working multiple jobs or caring for young children
- Insufficient sleep
- History of a previous fall-asleep crash or near miss
- Special considerations and separate evaluations are given to commercial drivers as many states and countries maintain medical standards for commercial driving licensure
Sleeplessness & Chronic Conditions
Studies show that sleep deprivation (and long sleep > 8 hours) places you at risk for higher rates of mortality and chronic disease, such as:
- Coronary heart disease and stroke
In today’s fast-paced, highly competitive world, it’s easier to want to postpone sleep in a bid to “get just a little more work done” or do some other essential tasks.
If you find yourself falling into this trap of sacrificing your sleep, you might want to consider the consequences of sleep deprivation on your driving and even your overall health.
When you drive while feeling sleepy or tired, you put not only yourself at significant risk but also other drivers. So, if your body indicates that it needs some shuteye, make time ASAP for that (even if it’s only a few minutes sleep).
If you think you may have a sleep disorder, talk to a sleep specialist to help resolve the problem.
- Nsc.org. 2021. Fatigued Driver – National Safety Council. [online] Available at: https://www.nsc.org/road-safety/safety-topics/fatigued-driving
- Ferrie, J. E., Kumari, M., Salo, P., Singh-Manoux, A., & Kivimäki, M. (2011). Sleep epidemiology–a rapidly growing field. International journal of epidemiology, 40(6), 1431–1437. https://doi.org/10.1093/ije/dyr203
- National Sleep Foundation. 2005 Sleep in America Poll.
- Tefft BC. Asleep at the wheel: the prevalence and impact of drowsy driving. AAA Foundation for Traffic Safety, Washington, DC 2010. https://aaafoundation.org/prevalence-impact-drowsy-driving/
- National Sleep Foundation. 2006 Sleep in America Poll
- Owens JM, Dingus TA, Guo F, et al. Prevalence of Drowsy Driving Crashes: Estimates from a Large-Scale Naturalistic Driving Study (Research Brief). AAA Foundation for Traffic Safety. Washington, DC 2018. Available at: https://publicaffairsresources.aaa.biz/wp-content/uploads/dlm_uploads/2018/01/FINAL_AAAFTS-Drowsy-Driving-Research-Brief.pdf
- Lyznicki JM, Doege TC, Davis RM, Williams MA. Sleepiness, driving, and motor vehicle crashes. Council on Scientific Affairs, American Medical Association. JAMA. 1998 Jun 17;279(23):1908-13. doi: 10.1001/jama.279.23.1908. PMID: 9634264.
- Bjerner B, Alpha depression and lowered pulse rate during delayed actions in a serial reaction test: A study in sleep deprivation, Acta Physiol Scand. 1949;19. https://psycnet.apa.org/record/1967-03821-001
- Akerstedt T. (1987). Sleep/wake disturbances in working life. Electroencephalography and clinical neurophysiology. Supplement, 39, 360–363. https://pubmed.ncbi.nlm.nih.gov/3308417/
- Torsvall, L., & Akerstedt, T. (1987). Sleepiness on the job: continuously measured EEG changes in train drivers. Electroencephalography and clinical neurophysiology, 66(6), 502–511. https://doi.org/10.1016/0013-4694(87)90096-4
- Williams, H. L., Lubin, A., & Goodnow, J. J. (1959). Impaired performance with acute sleep loss. Psychological Monographs: General and Applied, 73(14), 1–26. https://doi.org/10.1037/h0093749
- Durmer JS, Dinges DF. Neurocognitive consequences of sleep deprivation. Semin Neurol. 2005 Mar;25(1):117-29. doi: 10.1055/s-2005-867080. PMID: 15798944. https://pubmed.ncbi.nlm.nih.gov/15798944/
- Pack, A. I., Pack, A. M., Rodgman, E., Cucchiara, A., Dinges, D. F., & Schwab, C. W. (1995). Characteristics of crashes attributed to the driver having fallen asleep. Accident; analysis and prevention, 27(6), 769–775. https://doi.org/10.1016/0001-4575(95)00034-8
- Mara, J., 2021. Drowsy Driving. [online] One.nhtsa.gov. Available at: <https://one.nhtsa.gov/people/injury/drowsy_driving1/Drowsy.html#NCSDR/NHTSA>
- Owens, J.M., Dingus, T.A., Guo, F., Fang, Y., Perez, M., McClafferty, J. & Tefft, B.C. (2018). Prevalence of Drowsy Driving Crashes: Estimates from a Large-Scale Naturalistic Driving Study (Research Brief). Washington, DC: AAA Foundation for Traffic Safety. https://aaafoundation.org/prevalence-drowsy-driving-crashes-estimates-large-scale-naturalistic-driving-study/
- Research, N. (2021). Drowsy Driving: How to Stop Falling Asleep at The Wheel | National Center for Health Research. Retrieved Mar 10 2021, from https://www.center4research.org/drowsy-driving-stop-falling-asleep-wheel/
- Cappuccio, F. P., Cooper, D., D’Elia, L., Strazzullo, P., & Miller, M. A. (2011). Sleep duration predicts cardiovascular outcomes: a systematic review and meta-analysis of prospective studies. European heart journal, 32(12), 1484–1492. https://doi.org/10.1093/eurheartj/ehr007
- Buxton, O. M., & Marcelli, E. (2010). Short and long sleep are positively associated with obesity, diabetes, hypertension, and cardiovascular disease among adults in the United States. Social science & medicine (1982), 71(5), 1027–1036. https://doi.org/10.1016/j.socscimed.2010.05.041
- Cappuccio, F. P., Taggart, F. M., Kandala, N. B., Currie, A., Peile, E., Stranges, S., & Miller, M. A. (2008). Meta-analysis of short sleep duration and obesity in children and adults. Sleep, 31(5), 619–626. https://doi.org/10.1093/sleep/31.5.619
- Cappuccio, F. P., D’Elia, L., Strazzullo, P., & Miller, M. A. (2010). Quantity and quality of sleep and incidence of type 2 diabetes: a systematic review and meta-analysis. Diabetes care, 33(2), 414–420. https://doi.org/10.2337/dc09-1124
- Staner L. (2010). Comorbidity of insomnia and depression. Sleep medicine reviews, 14(1), 35–46. https://doi.org/10.1016/j.smrv.2009.09.003
- Neckelmann, D., Mykletun, A., & Dahl, A. A. (2007). Chronic insomnia as a risk factor for developing anxiety and depression. Sleep, 30(7), 873–880. https://doi.org/10.1093/sleep/30.7.873